There are many types of fire detectors in current use. For the purposes of this application fire detector is defined as a device which senses a fire in a structure by sensing heat, combustion gases or particulate matter in the atmosphere upon such detection the detector produces a signal such as a audible and/or visual alarm. In some circumstances such a detector may also activate other equipment to extinguish the fire detected such as sprinklers or extinguishers. Common names of such equipment include smoke Detector, fire alarm, thermal sensor, ionization detector, carbon monoxide detector, photoelectric detector, activator and the like.
Fire detectors are most commonly attached to inner surfaces of buildings such as walls and ceilings. Since smoke and hot air rise the devices are preferably matched to the ceiling. The first generation of such devices were wired into the buildings power supply in a nonintrerruptable connection. The second generation of such devices were battery powered and removable attached to the surface to allow changing of the battery. Many present building codes require that the devices have dual power sources such as the hard wired connection and a battery for emergency power. In addition, several detectors per floor are required.
In modern construction it is generally preferable from an esthetic viewpoint that internal building surfaces be free of obstructions and protrusions. To accomplish this goal recessed fixtures have been developed both for new construction and retrofitting. Such fixtures include recessed and indirect lighting appliances and recessed speakers.
A major disadvantage of present detectors is their visual appearance. Since they are attached to the interior surface they protrude from that surface. The protrusion from the surface breaks homogeneity of that surface and makes the detector all that more apparent when other fixtures are recessed. Accordingly, there is a long-standing need for a recessed fire detector.